Komatsu PC270-7 Fault Code E113: Complete Diagnostic Guide

What is Komatsu PC270-7 Fault Code E113?

Fault Code E113 on the Komatsu PC270-7 indicates a malfunction in the engine coolant temperature sensor circuit, specifically detecting an abnormally high voltage signal or open circuit condition in the sensor wiring.

This code is generated when the Electronic Control Module (ECM) receives a voltage reading outside the normal operating range (typically above 4.5V) from the coolant temperature sensor. The PC270-7's SAA6D107E-1 engine relies heavily on accurate coolant temperature data to manage fuel injection timing, engine protection systems, and optimal performance parameters. When this sensor circuit fails, the ECM cannot properly protect the engine from overheating or adjust combustion efficiency, potentially leading to severe engine damage or reduced operational performance.

Common Symptoms

When Code E113 is active on your PC270-7, operators typically experience:

• Engine warning lamp illuminated on the instrument cluster, often accompanied by audible warning beeps
• Temperature gauge reading abnormally low (cold) or showing no reading at all, even when engine is at operating temperature
• Reduced engine power or derate mode activation as the ECM enters a protective failsafe strategy
• Hard starting conditions when the engine is warm, as the ECM defaults to cold-start fuel maps
• Excessive black smoke during operation due to improper fuel-to-air ratio calculations

Potential Causes

The E113 code on used PC270-7 excavators typically stems from these technical failures:

• Coolant temperature sensor failure – internal sensor element degradation after 5,000+ operating hours
• Damaged or corroded wiring harness – particularly at known rub points near the thermostat housing and along the engine valley where the harness passes over the valve cover
• Loose or corroded electrical connectors at the sensor or ECM connection points, especially common in machines operating in wet or coastal environments
• Broken or shorted sensor wiring between the sensor and ECM, frequently caused by improper routing during previous repairs
• ECM internal circuit failure – rare but possible in high-hour machines with electrical system history

How to Troubleshoot and Fix Code E113

Step 1: Visual Inspection and Connector Check Begin by locating the coolant temperature sensor on the left side of the cylinder head near the thermostat housing. Disconnect the two-pin connector and inspect for corrosion, bent pins, or moisture intrusion. On used excavators, this connector frequently shows green corrosion. Clean connections with electrical contact cleaner and dielectric grease.

Step 2: Sensor Resistance Testing Using a digital multimeter, measure the resistance across the sensor terminals. A functioning sensor at 68°F (20°C) should read approximately 2,400-2,700 ohms. At operating temperature (190°F/88°C), resistance should drop to around 300-350 ohms. Readings showing infinite resistance (open circuit) or zero ohms (short circuit) confirm sensor failure requiring replacement (Komatsu part #6732-81-3140).

Step 3: Wiring Harness Continuity Check With the sensor disconnected, check for continuity between the sensor connector pins and the corresponding ECM pins (consult the PC270-7 electrical schematic). Also measure voltage supply from the ECM – it should provide approximately 5 volts reference voltage. Check for damaged insulation along known wear points where the harness contacts engine components.

Step 4: ECM Signal Verification Connect Komatsu diagnostic software (KOMTRAX Plus or compatible scan tool) to verify real-time voltage readings. If voltage remains above 4.5V with a known-good sensor installed, the ECM may require replacement or professional reprogramming.

For used excavators, always inspect harness routing and secure any loose wiring that may cause intermittent faults before investing in component replacement.

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Disclaimer: This guide provides general diagnostic procedures. Always consult the official Komatsu PC270-7 service manual and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with high-voltage systems.